Field of the Invention
The present invention is directed to a closure designed to hold a vacuum in an evacuated container and more particularly, to a one-piece closure containing multiple components formed in a single molding process. The invention is also directed to a closure including a foil or film that enhances the oxygen barrier properties of the evacuated container.
Description of Related Art
A commonly used method for collecting biological specimens, such as blood, is the employment of a needle assembly in conjunction with an evacuated container. The evacuated container provides the pressure differential necessary to facilitate flow and collection of the specimen through the needle assembly into the container. An example of an evacuated container used for specimen collection is the VACUTAINER® brand tube commercially available from Becton, Dickinson and Company. The evacuated tubes may be supplied with various additives to prepare the specimen for a particular test. The tubes may also be evacuated to a selected pressure that is less than atmospheric pressure to provide a preselected volume of drawn specimen. The evacuated tube is typically sealed with a pierceable closure which is capable of resealing after puncture and receipt of the specimen.
One type of needle assembly that can be used with an evacuated container can include a tubular body that holds a standard double-ended hollow needle at its distal end with one end, or a non-patient end, of the needle extending into the tube and the other end, or the patient end, of the needle extending out of the tube. The patient end of the needle is configured for connection to a specimen source, such as a patient's vein. The tubular body is configured to receive the evacuated container such that the pierceable closure is pierced by the non-patient end of the needle and the biological sample is drawn from the patient into the container by means of the vacuum within the container.
One type of pierceable closure can comprise multiple parts that are formed in separate molding steps and then assembled together. The multiple parts can include an outer cap body portion and an inner elastomeric pierceable portion that is designed to seal the interior portion of the container. The elastomeric material is of a type that can reseal after piercing and removal of the needle upon completion of specimen collection. Evacuated containers often have a limited shelf life because over time, oxygen can leak through the closure, reducing the effectiveness of the vacuum held within the container.
Expiration dates are determined through shelf-life testing performed under known environmental conditions. Shelf life of an evacuated tube is defined by the stability of the additive, as well as vacuum retention. If the environmental conditions under which evacuated tubes are stored are not consistent with those recommended by the manufacturer, it is possible that the draw volume of the tubes may be affected.
There is a need in the art for a multiple component one-piece closure that can be formed in a single molding process, thus reducing production costs, and which uses less molding materials, thus reducing raw material costs. There is also a need in the art for a closure having enhanced oxygen barrier properties increasing the shelf life of the evacuated container.